S13 - Session P2 - Effect of calcium concentration and medium pH on peach growth and chlorophyll content in vitro

Authors: Francisca Carrasco-Cuello *, Laia Jené, Ramon Dolcet-Sanjuan, Josep Rufat, Estanis Torres

Calcareous soils, typical on the Mediterranean area, have traditionally not been the most suitable for growing peach. The aim of the present work was to study the effect of calcium concentration and medium pH on peach rootstock Rootpac®20 growth and chlorophyll content by using GreenTray ® Temporary Immersion System bioreactor. For this purpose, eight different mediums based on the combination of two pH (5.7 and 7.5) and four calcium concentrations (3 mM, 1.5 mM, 0.99 mM, and 0.75 mM) were established. The results suggested that at pH 5.7 chlorophyll content and plantlet growth are positively influenced by calcium concentration increase, up to the regular Murashige and Skoog (1962) CaCl 2 content (2.99 mM). Otherwise, at pH 7.5 the highest calcium concentrations negatively affected plantlet growth and chlorophyll content. These effects could be explained by a calcium interaction with crucial micronutrient solubility at pH 7.5 promoting their precipitation. The findings indicated that the optimal calcium concentration for plant in vitro development is influenced by the medium pH. Regarding calcareous soils, pH adjusted to more acidic would lead to an increase of calcium uptake and plant biomass , based on in vitro . Under acid conditions, soil calcium applications would result in a significant improvement of plant growth, but a field approximation is needed.